Add JS wrapper for kredits kit

This makes it easier to deploy new DAOs and the deploy script is less
dependent on truffle

lib/kreditskit.js

@@ -0,0 +1,49 @@
+const ethers = require('ethers');
+
+const ABI = require('./abis/KreditsKit.json');
+const Addresses = require('./addresses/KreditsKit.json');
+
+class KreditsKit {
+
+  constructor(provider, signer, options = {}) {
+    let { address, abi, ipfsConfig } = options;
+
+    this.provider = provider;
+    this.signer = signer;
+    this.options = options;
+    this.address = address
+    this.abi = abi || ABI;
+  }
+
+  init() {
+    return this.provider.getNetwork().then((network) => {
+      this.address = this.address || Addresses[network.chainId.toString()];
+      this.contract = new ethers.Contract(
+        this.address,
+        this.abi,
+        (this.signer || this.provider)
+      );
+      return this;
+    });
+  }
+
+  appIdFor(contractName) {
+    // see appIds in KreditsKit.sol for more details
+    const knownContracts = ['Contribution', 'Contributor', 'Proposal', 'Token'];
+    return this.contract.functions.appIds(knownContracts.indexOf(contractName));
+  }
+
+  newDAO(options = {}) {
+    return this.contract.functions.newInstance(options).then(transaction => {
+      return transaction.wait().then(result => {
+        const deployEvent = result.events.find(e => e.event === 'DeployInstance');
+        return {
+          daoAddress: deployEvent.args.dao,
+          transactionHash: transaction.hash
+        }
+      });
+    });
+  }
+}
+
+module.exports = KreditsKit;